1. Field of the Invention
The present invention relates to a flat panel display device and a method of a manufacturing the same, and, more particularly, to a flat panel display device with improved electrical characteristics and reduced current leakage.
2. Description of Related Art
FIG. 1 is a cross-sectional view illustrating a conventional organic EL display device. A method of manufacturing the conventional organic EL display device is described below with reference to FIG. 1.
A buffer layer 12 is formed on a transparent substrate 11. The transparent substrate 11 is made of a glass or a synthetic resin. A poly silicon layer is deposited on the buffer layer 12 and patterned into a semiconductor layer 20 using a first mask. A first insulating layer 25 is formed over the entire surface of the transparent substrate 11.
Then, a first metal layer is deposited on the first insulating layer 25 and patterned into a gate electrode 35 using a second mask. Using the gate electrode 35 as a mask, an n-type impurity or a p-type impurity is ion-implanted into the semiconductor layer 20 to form source and drain regions 26 and 27.
Thereafter, a second insulating layer 30 is formed over the entire surface of the transparent substrate 11. The second insulating layer 30 serves as an interlayer insulating layer. Using a third mask, contact holes 31 and 32 are formed in the interlayer insulating layer 30. The contact holes 31 and 32 expose portions of the source and drain regions 26 and 27, respectively.
A second metal layer is deposited on the second insulating layer 30, filling into the contact holes 31 and 32. The second metal layer is patterned using a fourth mask to form source and drain electrodes 50 and 55. The source and drain electrodes 50 and 55 are electrically connected to the source and drain regions 26 and 27 through the contact holes 31 and 32, respectively.
Subsequently, a third insulating layer 40 is formed over the entire surface of the transparent substrate 11. Using a fifth mask, the third insulating layer 40 is etched to form a via hole 41 at a location corresponding to either of the source and drain electrodes 50 and 55. In FIG. 1, the via hole 41 is formed at a location corresponding to a portion of the drain electrode 55.
A transparent conductive material layer is deposited on the third insulating layer 40 and patterned using a sixth mask to form a pixel electrode 60. The pixel electrode 60 serves as an anode electrode. The pixel electrode 60 is electrically connected to either of the source and drain electrodes 50 and 55 through the via hole 41. In FIG. 1, the pixel electrode 40 is electrically connected to the drain electrode 55 through the via hole 41.
A fourth insulating layer 70 is formed over the entire surface of the transparent substrate 11. The fourth insulating layer 70 serves as a planarization layer. The fourth insulating layer 70 is etched using a seventh mask to form an opening portion 71. The opening portion 71 exposes a portion of the pixel electrode 60. An organic EL layer 80 is formed on the exposed portion of the pixel electrode 60 to cover the opening portion 71. Then, a cathode electrode 90 is formed to cover the organic EL layer 80. Therefore, the conventional organic EL display device is completed.
As described above, the method of manufacturing the conventional organic EL display device requires a seven-mask process. Therefore, this presents the difficulty that the manufacturing process is complicated and the production cost is increased.
Also, since the gate electrode 35 is used as a mask during an ion-implanting process to form the source and drain regions 26 and 27, the gate electrode 35 may become damaged during manufacturing, thereby deteriorating electrical characteristics of the flat panel display device.
In addition, when a lightly doped drain (LDD) structure or an offset structure is employed in order to improve an on/off current ratio, an additional mask process is required. In that case, a process to anodize the gate electrode can be employed so that an additional mask process is not required. However, this requires additional equipment for the anodizing process, thereby increasing the production cost.
To overcome the difficulties described above, preferred embodiments of the present invention provide a flat panel display device having a simplified manufacturing process.
It is another object of the present invention to provide a flat panel display device having excellent electrical characteristics.
It is a still object of the present invention to provide a flat panel display device which can reduce a leakage current.
In order to achieve the above objects, the preferred embodiments of the present invention provide a flat panel display device, comprising: a semiconductor layer formed on an insulating substrate; source and drain electrodes directly contacting both end portions of the semiconductor layer, respectively; a pixel electrode having an opening portion formed thereon; a first insulating layer formed over the remaining portion of the insulating substrate except for the opening portion; a gate electrode formed on a portion of the first insulating layer over the semiconductor layer; and source and drain regions formed in both end portions of the semiconductor layer.
The source and drain electrodes include a pixel electrode material layer, a metal material layer and a capping insulating material layer stacked sequentially. The pixel electrode extends from either of the source and drain electrodes. The organic EL display device further includes a storage capacitor including first and second capacitor electrodes with a dielectric layer interposed therebetween. The first capacitor electrode includes the pixel electrode material layer and the metal material layer stacked sequentially. The second capacitor electrode includes a gate electrode material layer. The dielectric layer includes the capping insulating layer and the first insulating layer stacked sequentially.
The source and drain regions include an offset region formed in a portion of the semiconductor layer between the source and drain electrodes and the gate electrode. The source and drain regions include low-density source and drain regions formed in a portion of the semiconductor layer between the source and drain electrodes and the gate electrode, thereby forming a lightly doped drain (LDD) structure.
The organic EL display device further includes first and second spacers. The first spacer is formed on side wall portions of the source and drain regions. The second spacer is formed on side wall portions of the gate electrode and the opening portion. The organic EL display device further includes a second insulating layer for planarization on the remaining portion of the first insulating layer except for the opening portion. The gate electrode includes a metal material layer and a capping insulating layer stacked sequentially.
The present invention further provides a method of manufacturing a flat panel display device, comprising: forming a semiconductor layer on an insulating layer; ion-implanting an impurity having a first conductivity into the semiconductor layer; forming source and drain electrodes, the source and drain electrodes directly contacting both end portions of the semiconductor layer; ion-implanting an impurity having a second conductivity into the semiconductor layer to form high-density source and drain regions and a channel area, the high-density source and drain regions directly contacting the source and drain electrodes; forming a first insulating layer over the entire surface of the insulating substrate; forming a pixel electrode having an opening portion formed thereon; and forming a gate electrode on a portion of the first insulating layer over the semiconductor layer.
The method further includes forming a contact hole contemporaneously with forming the pixel electrode having the opening portion, the contact hole contacting the first capacitor electrode and the gate electrode.